A number of motionless mixer types exist, such as Multiflux, helical and others. These mixer types, for the most part, implement a similar general principle to mix fluids together. In these mixers, fluids are mixed together by dividing and recombining the fluids in an overlapping manner. This action is achieved by forcing the fluid over a series of mixing elements and baffles of alternating geometry. Such division and recombination causes the layers of the fluids being mixed to thin and eventually diffuse past one another, resulting in a generally homogenous mixture of the fluids. This mixing process has proven to be very effective, especially with high viscosity fluids.
Static mixers are typically constructed of a series of mixing elements and alternating baffles, of varying geometries, usually consisting of right-handed and left-handed mixing baffles located in a conduit to perform the continuous division and recombination. Such mixers are generally effective in mixing together most of the mass fluid flow, but these mixers are subject to a streaking phenomenon, which has a tendency to leave streaks of completely unmixed fluid in the extruded mixture. The streaking phenomenon often results from streaks of fluid forming along the interior surfaces of the mixer conduit that pass through the mixer essentially unmixed.
Moreover, there have been previous attempts made to maintain adequate mixer length while trying to address the streaking phenomenon. In one example, the traditional left-handed and right-handed mixing baffles can be combined with flow inversion baffles, such as the specialized inverter baffles described in U.S. Pat. No. 7,985,020 to Pappalardo and U.S. Pat. No. 6,773,156 to Henning. However, these known types of flow inversion baffles may cause a high backpressure within the mixer conduit and may also disrupt the mixing layers of material as a result of the complex movements required for fluid flow through the flow inversion baffles. That disruption of the mixing layers can reduce the efficiency of mixing enabled by the downstream mixing baffles, which means that more elements and length may be required in the static mixer to achieve the desired mixing effects. In this regard, the streaking phenomenon is handled by the flow inversion baffles, but these also present further disadvantages to overcome in the static mixer as a whole.
Therefore, it would be desirable to further enhance the mixing elements used with static mixers of this general type, so that mixing performance is further optimized at each mixing element, and preferably without generating high amounts of backpressure.